Israel Medical Association Journal

Background: Oral anticoagulation with warfarin can lead to life-threatening events as a result of either over-anticoagulation or undertreatment. One of the main contributors to an undesirable warfarin effect is the need to adjust its daily dose for a specific patient. The dose is adjusted empirically based on the experience of the clinician, a method that is often imprecise. There is currently no other well-accepted method for predicting the maintenance dose of warfarin.

Objective: To describe the application of an artificial neural network to the problem of warfarin maintenance dose prediction.

Methods: We designed a neural network that predicts the maintenance dose of warfarin. Data on 148 patients attending a large anticoagulant clinic were collected by file review. Using correlational analysis of the patients' data we selected the best input variables. The network was trained by using the back-propagation algorithm on a subset of our data and the results were validated against the rest of the data. We used a multivariate linear regression to create a comparable model.

Results: The neural network generated reasonable predictions of the maintenance dose (r = 0.823). The results of the linear regression model were similar (r = 0.800).

Conclusion: Neural networks can be applied successfully for warfarin maintenance dose prediction. The results are promising, but further investigation is needed.
 

Background: Various medical centers in Israel have recently incorporated electronic medical record systems. Knowing the EMR[1] systems’ features and pattern of use is an essential step for developing locally and nationally integrated systems.

Objectives: To evaluate the status of EMR systems in all major general hospitals in Israel in terms of the applications used and the patterns of use.

Methods: Structured questionnaires were sent to hospital directors and directors of medical informatics units of 26 general and pediatric hospitals serving the vast majority of the population in Israel. The qheuestionnaire included questions pertaining to the EMR systems, their usage and the attitude of the participants to data security issues.

Results: Of the 26 general hospitals 23 (88.4%) returned the questionnaires. Of these, 21 (91.3%) use EMR systems. Twenty-seven different types of systems are in use in Israeli hospitals, and generally more than one type is used in a hospital. [YD1] Physicians work with EMR systems in over 98% of the departments. Also, the EMR systems are used for clinical admission and discharge in over 90% of the departments and for medical daily follow-up in about 45%.

Conclusions: Most of the hospitals in Israel use EMR systems but there is no standard data model. Physicians are the main users but the amount of data entered is still limited. Adoption of standards is essential for integration of electronic patient records across Israeli healthcare organizations.

Background: Until recently trimethoprim-sulfamethoxazole was the drug recommended in the Leumit Health Fund for the empiric treatment of uncomplicated urinary tract infection in women. However, due to increased uropathogen resistance to this drug, the fund has designated nitrofurantoin as its new drug of choice.

Objectives: To evaluate the potential economic impact of implementing this new pharmaco-policy.

Methods: Using data derived from the electronic patient records of the Leumit Health Fund we identified all non-recurrent cases of women aged 18–49 with a diagnosis of acute cystitis or UTI[1] without risk factors for complicated UTI and empirically treated with antibiotics throughout 2003. The final sample comprised 5,489 physician-patient encounters. The proportion of cases treated with each individual drug was calculated, and the excess expenditure due to non-adherence to the new guideline from the perspective of the health fund was evaluated using 5 days of therapy with nitrofurantoin as the reference treatment.

Results: Ofloxacin was the most frequently prescribed drug (30.24%), followed by TMP-SMX[2] (22.43%), cephalexin (15.08%), and nitrofurantoin (12.59%). The observed net aggregate drug expenditure was 2.3 times greater than expected had all cases been treated with nitrofurantoin according to the guideline duration of 5 days. The cost of treatment in 53% of the cases exceeded the expected cost of the guideline therapy.

Conclusions: Successful implementation of the new drug policy will likely improve quality of care and reduce costs to the health fund.

Background: The appearance of pericarditis following insertion of a permanent pacemaker is not widely acknowledged in the literature.

Objectives: To describe our experience with pericarditis following 395 permanent pacemaker implantations over 2 years.

Methods: We retrospectively reviewed the medical records of 395 consecutive patients in whom new pacing systems or pacemaker leads had been implanted over a 2 year period. We searched the records for pericarditis that developed within 1 month after pacemaker implantation according to the ICD-9 code. The incidence, clinical picture, response to treatment and relationship to lead design and location were studied.

Results: Eight cases (2%) of pericarditis following implantation were detected. Clinical manifestations in all patients were similar to those of post-pericardiotomy syndrome and included chest pain (n=7), friction rub (n=1), fever (n=2), fatigue (n=2), pleural effusion (n=2), new atrial fibrillation (n=2), elevated erythrocyte sedimentation rate (n=4) and echcardiographic evidence of pericardial effusion (n=8). All affected patients had undergone active fixation (screw-in) lead implantation in the atrial position. The incidence of pericarditis with screw-in atrial leads was 3% compared to 0% in other cases (P < 0.05).

Conclusions: Pericarditis is not uncommon following pacemaker implantation with active fixation atrial leads. Special attention should be paid to identifying pericardial complications following pacemaker implantation, especially when anticoagulant therapy is resumed or initiated. The use of passive fixation leads is likely to reduce the incidence of pericarditis but this issue should be further investigated.

Background: Transmission of Pseudomonas aeruginosa among cystic fibrosis patients attending health camps has been reported previously.

Objectives: To determine the transmission of P. aeruginosa among CF[1] patients during three winter camps in the Dead Sea region in southern Israel.

Methods: Three consecutive CF patient groups were studied, each of which spent 3 weeks at the camp. The patients were segragated prior to camp attendance: patients who were not colonized with P. aeruginosa constituted the first group and colonized patients made up the two additional groups. Sputum cultures were obtained upon arrival, at mid-camp and on the last day. Environmental cultures were also obtained. Patients were separated during social activities and were requested to avoid social mingling. Isolates were analyzed by antibiotics susceptibility profile and by pulsed field gel electrophoresis.

Results: Ninety isolates from 19 patients produced 28 different fingerprint patterns by PFGE[2]. Isolates from two siblings and two patients from the same clinic displayed the same fingerprint pattern. These patients were already colonized with these organisms upon arrival. Two couples were formed during the camp, but PFGE showed no transmission of organisms. All other patients' isolates displayed unique fingerprint patterns and were distinguishable from those of other attendees, and none of the P. aeruginosa-negative patients acquired P. aeruginosa during camp attendance. Environmental cultures were negative for P. aeruginosa.

Conclusions: We were unable to demonstrate cross-infection of P. aeruginosa among CF patients participating in health camps at the Dead Sea who were meticulously segregated.

Background: Splanchnic nerve stimulation evokes adrenomedullary catecholamine secretion via acetylcholine release and occupation of nicotinic cholinergic receptors on chromaffin cells.

Objectives: To assess whether among cultured adrenomedullary cells there exists a population that tonically secretes acetylcholine. If so, then blockade of enzymatic breakdown of acetylcholine by addition of a cholinesterase inhibitor to the medium would increase occupation of nicotinic receptors by endogenous acetylcholine and thereby induce catecholamine release.

Methods: Primary cultures of bovine adrenomedullary cells in 24-well plates (1 million cells per well) were incubated after 48–72 hours with fresh incubation medium (control), medium with added secretagogues (nicotine, angiotensin II, or K+) or the acetylcholinesterase inhibitor, edrophonium (10-7 to 10-³ M), for 1–20 minutes. Fractional release rates of epinephrine, norepinephrine and dopamine were compared to a control. We also examined whether co-incubation with edrophonium enhanced the effects of the secretagogues. All experiments were performed in quadruplicate and repeated three times.

Results: Nicotine, angiotensin II, and K+ each elicited time-related release of epinephrine, norepinephrine and dopamine by up to fourfold compared to the control. At all tested concentrations, edrophonium had no such effect. Co-incubation with edrophonium also failed to augment the secretory responses to nicotine, angiotensin II, or K+.

Conclusion: Bovine adrenomedullary cells in primary culture do not include a population of tonically active cholinergic cells.

Background: The indication for aortic valve replacement in patients with significant aortic stenosis is symptomatology. Aortic stenosis may be associated with bleeding from colonic angiodysplasia, resulting in anemia. Persistent anemia in such patients, despite lack of an identifiable source of bleeding, is not considered an indication for valve replacement.

Objectives: To report our experience with two elderly female patients who suffered from severe asymptomatic aortic stenosis, low levels of large von Willebrand factor multimer (10% and 5% respectively) and persistent anemia requiring multiple blood transfusions.

Methods: Both patients underwent an intensive work-up, but a source of bleeding could not be identified. Aortic valve replacement was performed in both patients.

Results: Aortic valve replacement abolished the need for further blood transfusions during a follow-up period of 20 months with normalization of the vWF[1] multimer level (20% and 30% respectively).

Conclusion: We suggest that aortic valve replacement be considered in selected patients with severe, otherwise asymptomatic aortic stenosis, who suffer from persistent anemia requiring multiple blood transfusions, lack an identifiable source of bleeding and have low levels of large vWF multimers.